Generator armature test



Sept. 29, 1953 Original Filed Oct. 7,v 1948 F. J. FOUST ETAL GENERATOR ARMATURE TEST 8 Sheets-Sheet l INVENTORS mw M 6 74 Sept. 29, 1953 F. J. FOUST ETAL GENERATOR ARMATURE TEST Original Filed Oct. 7, 1948 8 Sheets-Sheet 2 mmvroxs DWIGHT O. CE/M EDGE-B7 A. THMPJ'OIV Sept. 29, 1953 F. J. VFOUST ET AL 7 2,554,065

GENERATOR ARMATURE TEST.

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Patented Sept. 29, 1953 GENERATOR ARMATURE TEST Floyd J. Foust, Olven W. Childress, Jr., Dwight 0. Crim, and Robert A. Thompson, Anderson, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Original application October 7, 1948, Serial No. 53,362, new Patent No. 2,593,131, dated April 15, 1952. Divided and this application October 19, 1951, Serial No. 259,332

3 Claims. (01. 324-51) This invention relates to the testing of armatures of dynamoelectric machines and its object is to provide apparatus for testing the armature for grounded circuits, open circuits and short circuits. This application is a division of application Ser. No. 53,362, now Patent No. 2,593,131. The disclosed embodiment of the invention provides mechanical means with which a dynamo armature can be easily coupled for efifecting its rotation during the test and contactors engageable with its commutators and connected with electrical circuits which operate successively first, to burn out small metallic particles making a connection between the commutator bars and ground, second, to test for a permanent ground, and third, to subject the armature to a high frequency test during which the armature coils are connected with a resonant circuit inductively related to an oscillator. The high frequency test circuit includes a meter which will indicate whether the armature is good or whether any of its coils are short-circuited or open-circuited or grounded.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Figs. 1 and 2 together form a front elevation of a mechanism which receives and rotates the armature during the test, certain switches (shown in Fig. 3) being omitted for sake of clearness.

Fig. 3 is a side view in the direction of arrow 3 of Fig. 2 and includes the switches omitted in Fig. 1.

Fig. 4 is a fragmentary view on line 4-4 of Fig. 2.

Fig. 5 is a fragmentary top view in the direction of arrow 5 of Fig. 4.

Fig. 6 is a view in section of another type of adapter.

Figs. 7, 8, 9, 10 and 11 are sectional views taken, respectively, on lines 'l-'l, 8-8, 99,.

I0l0 and I|H of Fig. 1.

Fig. 12 is a view in the direction of arrow [2 of Fig. 1.

Fig. 13 is a sectional view on line |3-I3 of Fig. 12.

Fig. 14 is a fragmentary sectional view on line I4-l4 of Fig. 11.

Fig. 15 is a plan view of a commutator contact roller supporting unit.

Fig. 16 is a view similar to Fig. 15 with the top plate of said unit removed.

by a screw 31.

Fig. 17 is a sectional view on line Il-Il of Fig. 16.

Fig. 18 is a bottom view of the unit.

Fig. 19 is an end view in the direction of arrow IQ of Fig. 18.

Fig. 20 is a sectional view on line 2026 of Fig. 19.

Fig. 21 is a view of a group of parts of the roller supporting unit.

Fig. 22 is a wiring diagram of electrical apparatus including the testing circuits.

Fig. 23 is a portion of the diagram of Fig. 22 showing its connections with commutator segments.

Fig. 24 is a diagram of a resonant curve.

Fig. 25 is'a diagram showing meter readings under difierent conditions.

Fig. 26 is a timing chart.

Referring to Figs. 1, 2 and 3, a plate is supports a plate I 1 which supports an electric motor 20 (Fig. 1) which drives, through pulley 2|, belt 22 and pulley 23, speed reducing gearing contained in a housing 24 and connected by coupling members 25 and an intermediate disc 26 with a shaft 21 which is journaled in a bearing 29 supported by a bracket 28. Shaft 21 is connected with a bevel gear 30 meshing with a bevel gear 3| with a shaft 32 (Fig. 4) journaled in bearing 33 supported by a bracket 34 supported by plate Shaft 32 has a flange 35 which receives one end of a tubular shaft 36 secured to the shaft 32 Shaft 36 provides a recess 38 and a pin 39 extending into the recess. Recess 38 is adapted to receive one of a series of adapters 40 having central bores 4| of different diameters which receive armature shafts. The adapter 46 has a. shank 4! provided with a bayonet slot 42 cooperating with the pin 39 to secure the adapter to the shaft 36. The adapter 40 has a bore 43a for receiving an end portion of the armature shaft and a bore 431; of larger diameter for receiving a portion of the armature shaft of larger diameter. The adapter 40 has a groove 44 for receiving an elastic band 45 which urges inwardly a plurality of balls 46 guided by transverse holes 41. Inward movement of the balls 46 is limited by their engagement with the conical surface 48 of the adapter. The function of the balls 46 is to engage a groove orkey-way slot in the armature shaft and thus provide driving engagement between it and the shaft 36. The cross slots 49 in the exposed end of the adapter 40 will receive a tool such as a wide-bit screwdriver used to tighten the bayonet slot connection between the adapter 40 and the shaft 36.

3 Instead of using a shaft 36 with an adapter, the shaft 58 (Fig. 6) having an integral adapter can be substituted. The parts of shaft 58 and parts associated therewith which correspond to those of the adapter 48 are designated by the same numbers with primes aflixed.

Plate I (Figs. 4 and 5) supports a ring 5| having a bore 52 which clears the armature commutator 68 and a bore 53 which clears the wires leading from the armature coils to the commutator 68. Before the test begins, carbon contact rollers 62, 63 and 64 move from the normal positions into contacting positions 62', 63 and 64'. Rollers 62, 63 (Fig. are pivoted on nuts 62a, 63a, respectively, attached by screws 62a, 63a, respectively, to arms 62!) and 83b, e pe tively, pivotally supported by screws 62c and 63c respectively (Fig, 16), attached to metal plates 62d and 63d, respectively, which are attached. by

screws 65 to a carriage 68 and insulated there- I from by a non-conducting plate 66 having ribs 61 (Fig. 21). Carriage 68 has rollers 68 guided by bars 18 (Fig. 20) and a plate 1I attached to bars 18 by screws 12. Screws 13 (Figs. 1 and 2) attach plate H to plate I5. The carriage 68 is urged right (Figs. 1, 2 and 17) by springs 14, (Figs. 17 and 18) each attached at one end to a plate 15 which screws 16 attach to. carriage 68 and at the other end to a clip 11 which screws 18 attach to the carriage 68. When permitted to do so, springs 14 urge the carriage toward the right or down in Fig. 5 to cause the rollers 62 and 63 to engage the commutator 68 and to be spread apart so as to move in a position 62' and 63. This spreading of the rollers isresisted by springs 62c and 634:, respectively (Fig. 18), connecting the arms 62b and 63b, respectively, with the screws 62g and 63g attached to plates 62d and 63d, respectively, and urging the arms into engagement with pins 621 and 63]. respectively. The roller 64 is pivotally supported by a lever 88 (Figs. 2, 4 and 5) which is pivotally supported by a screw 8I attached to an insulator 82 attached to plate I5. Lever 88 is pivotally connected with a screw 83 (Figs. 4 and 5) threadedly connected with a sleeve 84 which is threadedly connected with a rod 85 which passes through five non-conducting washers, two of which numbered 86, are at the ends of the group, washers 81 next to the ends and an intermediate washer 88 supported by an arm 88 which as shown in Fig. 16 is integral with or attached to the carriage 68. The rod 85 is surrounded by springs 88 confined between the end washers 86 (Fig. 2) and nuts 8| threaded on rod 85.. The function of springs 88 is normally to center the rod 85 relative to the arm 88.

Movement of the carriage 68 toward the commutator causes the roller 64 to move into position 64 concurrently with movement of rollers 62 and 63 into engagement with the commutator.

The rollers 62, 63 and 64 are normally held out of engagement with the commutator by the engagement of left end surface 83 (Figs. 1 and 16) of a slot 84 with a Screw 85 carried by a lever 86 attached to a bracket 88 attached to plate I1 (see also Fig. '7). Lever 86 carries a screw 88 engageable with a bar I88 which is guided for vertical movement in grooves provided by bracket 88 and is retained by plates I8l secured by screws I82 to bracket 88. At its lower end, the bar I88 carries a pin I83 supporting a roller I84 normally received by a recess M81) in the lobe 188g, of a cam plate I88. In the normal position of cam I88, shown in Fig. 7, the carriage 68 is caused to be retained in the position shown in Figs. 1 and 2 against the action of springs 14 (Fig. 18) so that the rollers 62, 63 are normally held out of engagement with the commutator 68.

Referring to Fig. 13, screws I88 secure to cam I88, cams I85, I86 and I81 and screws II8 secure cam I88 to a hub III which is journaled on a clutch member II2 attached to shaft 21 and located between cam I88 and a disc Illa which screws IIIb attach to hub III. Hub III is slightly wider than the member II2. Member II2 has clutch teeth I I3 which are adapted to be engaged by a clutch dog II4 (Fig. 11), which an elastic band II5 urges toward the clutch member H2. The dog II4 carries a rod or pin II6 adapted to be engaged by a clutch throw-out cam II1 provided by a bar II8 which is guided for vertical movement by a bracket II8 (Fig. 11) attached to plate I1, the bar being retained by plates I28 and I2I secured to the bracket by the screws I22 and I23 respectively. Bar II8 extends through a hole I24 in plate I5 and carries a handle or knob I25. By pushing the knob I25 down, the bar I I8 moves down until the stop pin I26 strikes the bracket II8; and, during this movement, the clutch throw-out cam H1 is moved away from the path of movement of the pin I I6 and dog I I4 can move right (Fig. 11) under the action of band H5 in order toconnect the shaft 21 with the drum III and the cams I85, I86, I81, I88 connected therewith. Normally the dog is held out of engagement with the clutch member II2 by a spring I21 confined between a portion of the bracket H8 and the pin I28 attached to the bar II8. Spring I21 pushes the bar upwardly until a screw I28 carried thereby strikes the plate I2 An instant after the knob I25 is pushed down the drum III starts rotating to move the pin [I6 (Fig. 14) away from the cam II1. Then the knob I25 can be released so that the cam I I1 will be returned to its clutch throw-out position so that the drum III will make one revolution. During this revolution cam I88 makes one revolution to permit the carriage to move toward the commutator so that the rollers 68, 62 and 64 will engage it. coincidentally with the engagement of cam II1 with the pin II6 to disengage the clutch, the cam I88 has arrived in such position as to cause the carriage to be retracted and to present the groove I88b for engagement by the roller I84 (Fig. '7). In order that the cam I08 will not be moved past its position a brake is provided. This brake comprises a shoe I38 (Fig. 1) attached to a bar I3I providing a hole for receiving a stud I32 threaded into the bracket H8 and surrounded by a spring I33 confined between the bar I3I and a nut I34 threaded on the stud. Near its upper end bar I3I has a hole which receives a pin I35 which, as shown in Fig. 3, is attached to bracket II8. During the test the cams I-I88 make one revolution and then stop and during that time the tested armature is rotated sufllciently for the required test.

The testing apparatus includes switches S3, S2 and SI which are operated respectively by cams I85, I86 and I81 (Figs. 8, 9 and 10 respectively). Cam I81 (Fig. 10) operates also a switch S8. Each of these switches has a roller I48 supported by blade I4I for operating a switch contact actuator. he switches SI, S2, S3 and S8 are supported by a plate I44 (Figs. 1, 3) attached to bearing bracket 28, A switch S8 (Figs. 1, '7) supported by a plate I45 attached to bracket 88 has its operating roller I40 engageable with the lug Ia provided by bar I00. Switch S8 is normally closed all during the test cycle and switches SI, S2, S3, S9 are normally open switches closed at diiferent times during the test cycle.

Before starting to test, switch S4 (Fig. 22) is closed to connect a current source (at 110 v. A. C. for example) with wires 20I and 202. Lamp LI shows green to show that $4 has been closed. If switch S8 is closed as it should be when the test cycle starts, lamp L3 shows yellow. At the end of the test cycle, the lamp L3 goes out to indicate the test cycle has ended.

To test an armature after it is connected with the shaft 30, the knob I25 is pressed down to start the cams rotating and the rollers 62, B3 and 64 are advanced into engagement with the commutator t0 and then switch SI is closed which connects coil 50 of switch S with wires 20I and 202. Switch S5 then bridges its contacts 5a and 5b, thereby connecting primary coil I p of transformer TI with wires MI and 202 and connecting secondary coil I s by wires 4x and 4 with roller 64. This applies 50 volts to the commutator segments which are connected together by the armature coils. The application of this voltage causes the burning out of any metal particles which might connect the bars of the commutator with the metal core of the commutator which is grounded through the apparatus.

Then switch SI opens to effect opening of switch S5 and switch S2 closes to connect coil 60 of switch S5 with wires 20I and 202 which causes switches S5 to bridge its contacts 6a and 6b, thereby connecting primary coil 2p of transformer T2 with wires 20I and 202 and connecting secondary coil 28 of transformer T2 with contact roller 54 through wires 4a: and I and connecting coil 2s with ground through coil relay REIc and resistance RI 0 with ground. This causes the application of 500 volts to the commutator. If the commutator is not grounded coil REIc is not energized and relay REI does not close. If the commutator is grounded, contacts RE Ia of relay REI close. Coil REZc of relay REZ is energized through the following circuit: Wire 20I normally closed switch S8 (remaining closed until near the end of the cycle), switch S9 (normally open but closed by cam I01 near the end of the ground test), contacts REIa of relay REI, wire 206, coil R1320 of relay RE Z and wire 202. Relay REZ closes its contacts REM and REZb; and when, contacts REZb are closed, RE2c remains energized through the following circuit independent of contacts REIa of relay REI, wire 20I, switch S8, wire 203, contacts REZb, coil RE2c, wire 202. When contacts REZa close red lamp I2 burns through the following circuit: Wire 20I, switch S8, wire 203, contacts REZa, wire 205, lamp I2, wire 202. Lamp I2 burns red to indicate ground and remains closed until switch S8 opens near the end of the cycle. In case there is no ground, lamp I2 does not burn.

The last event in the cycle is known as the high frequency test. Before describing that test, the high frequency apparatus will be described. There is a power pack including transformers T3, T t, T5 and T6 whose respective primary windings 3p, 4p, 5p, 519 are connected with wires 20I and 202. Secondary 3s of transformer T3 is center-tapped to ground and its ends are connected with the plates of rectifier tubes V3 and V4 whose cathodes are heated by current furnished by secondary winding 4s of transformer T4. The rectified current from tubes V3 and V4 is filtered by network comprising chokes HI and H2 and condensers-C6 and C1; and the filtered current passes along wire 2I'I to variable voltage divider resistance R2 and to fixed divider resistances R5 and R6.

Wire 203 connects resistance R2 with grid 2I2 of tube VI. Wire 204 connects resistance R2 with resistances R3 and R4 connected respectively with grid 22I of tube V2 and with condenser C9 also connected with plate 220 of tube V2. One terminal condenser OH) is connected with ground of resistance R6 and its other terminal is connected with the junction of resistances R5 and Rt and with wire 205 connected with the cathode 223 of tube V2. The cathode heater 224 of this tube is connected through connections 11, y with the similarly marked terminals of secondary winding 5s of transformer T5. The secondary Winding 6s of transformer T6 is center tapped to ground and is connected as indicated by cc, a: with cathode 2 IA of tube VI. Grid 2! 3 of tube BI is connected with ground through condenser C5 and is also connected with a grid coil GC connected with adjustable resistance RI which is grounded and has its junction with coil C-.C connected with one terminal of condenser C4 and whose other terminal is connected with ground and also with a wiper 2I5 adjustable along resistance RI. Grid 2II of tube VI is grounded. Plate 2 I0 of tube VI is connected by wire 2I6 with terminals of condenser C2 and a plate coil PC whose other terminals are connected with wire 2II which is connected with the power pack. Wire 2 I I is also connected with ground condenser C3.

The network which includes tube VI and coils GC and PC provide what is generally known as an Armstrong oscillator. Coils PC and GC and a work coil WC are inductively related by concentric location. The oscillator is adjusted for a suitable frequency, for example 5 kc. per second. One end of coil WC is connected with the grounded end of condenser 01 which wire 3 connects with the other terminal coil WC and with the commutator contacting roller 63 through contacts 30 which are bridged when coil 7c of switch S1 is energized. When contacts 20 of switch S1 are bridged, contact roller 62 is connected by wire 2 with a condenser C8 connected with resistance R! which is grounded and which has a wiper 225 connected with grid 222 of tube V2. When contacts to of switch S7 are bridged contact roller 64 is connected by wire 4 with ground and through a variable resistance RII with a meter M connected by wire 4y with a terminal of condenser C0 whose other terminal is connected with plate 220 of tube V2.

Thehigh frequency test is started by the closing of switch S3 which connects coil 10 of relay switch S1 with wires 20I and 202 to efiect the bridging of pairs of contacts 20, 4c and 3c for the purpose of completing the circuits between the commutator engaging rollers and the test circuit. A portion of the test circuit is shown in Fig. 23 in simplified form. The input circuit may be considered to include the grounded end of coil WC, wire 3, contact roller 63, the contacted commutator bars, armature coils ac between roller 63 and roller 64, wire 4 and its ground connection with the coil WC. The output or meter circuit includes contact roller 64, wire I meter M, condenser C9, tube V2, condenser CID, ground to resistance R'I, condenser C8, wire 2 and contact roller 62 and armature coils ac between rollers 62, 64. The reading of the meter M is under con- 1JIOI y e l' hq e grid 222 is connected with wi er 225 of resistance R1. If the armature is good, that is, it has no open circuited coils. shortcircuited coils and no grounded coils, it combines with work coil WC and condenser CI to provide a circuit which has a resonance approaching full resonance with respect to the oscillator. In Fig. 24, curve RR represents relative resonance. If the armature is good, point A on curves RR represent the relative resonance of the armature and work coil circuit to the oscillator. Point A is well up on the gradual scope of the resonance curve but is somewhat below the maximum. If the armature is good the meter reading is of a substantial constant even though the armature is rotating slowly and adjustment of resistance RI I can be made so that the meter will read, for example, as represented by line A in Fig. 25 90 units. If the armature has one or more open circuited coils, the relative resonance will increase to B on curve RR; and the meter needle will fluctuate between 90 units and an increased reading of 110, for example, as represented by line B in Fig. 25. If the armature has shorted turns, its relative resonance will be decreased to a value represented by point C on curve RR; and the meter needle will fluctuate between 90 units and a lower value such as 70 units, for example, as represented by line C, Fig. 25. If the armature is grounded, the relative resonance will be decreased to a much lower value such as represented by point D on curve RR; and the meter will read a much lower value, for example 30 units, as represented by line D in Fig. 25.

The voltage impressed on grid 222 of tube V2 is under control by the resonance of the work coil circuit relative to the oscillator circuit. If the relative resonance is greater than normal for a good armature, such as value B, grid 222 is so biased as to permit tube V2 to pass more current hence the meter M will read higher. relative resonance is less than normal grid 222 is so biased as to permit tube V2 to pass less current and the reading of meter M will be lower.

The high frequency test provides for detection of good, open-circuited, shorted or grounded armature by the use of resonance comparing means comprising a first circuit including a condenser and a coil subjected to high frequency and a second or armature circuit including armature coils, a second condenser and a second coil connected therewith and inductively coupledwith the coil of the first circuit and a device for indicating the degree of resonance of armature circuit with respect to the first circuit. A meter capable reading from to 1 milli-amperes, when used with an amplifier is asuitable indicating device. Its scale should be read from 0 to 120 units.

Other suitable electrical values are as follows:

Condensers C1, C2. C3 2 mid, 1000 volts Condenser C4 1 mfd'., 600 volts Condenser C .02 mfd. 600 volts Condensers C6, C7, CL... 2, mfd., 1000 voltsv Condenser C9 1 mfd., 600 volts Condenser C 50 mfd., 150 volts Resistance R1 25,000 ohms, 50 watts Resistance R2 5000 ohms, 200 watts Resistance R3 10,000 ohms, 10 watts Resistance R4 10,000 ohms, 600 volts Resistance R5 50,000 ohms, 100 watts Resistance R6 '750 ohms, 20 watts Resistances R1, R5 250,000 Ohms, 1 Watt Chokes H1, H2 10 henries, 200 milliamps.

When the 8 Transformer T1 50 volts, 1000 V. A. Transformer T2 500 volts, 5 V. A. Transformer Ta 1100 volts, 200 ma.

center tap. Transformer T4 2.5 volts, 5 amp. Transformer T5 6.3 volts, 3 amp. Transformer Ts 10.0 volts, 10 amp.

center tap. Tube V1 #813 Tube V2 #6L6 Tubes V3, V4 #816 Fig. 26'shows the timing of the apparatus relative to motion of cams I05, I00, I01, I08 for one revolution. The zero positions of these cams are shown in Figs. 7 to 10. At about 7, the rollers 62, 63, 64 begin to advance to the commutator. From 15 to the commutator is subjected to burn out" voltage. From to the armature is subjected to the ground test. From to about 360 the armature is subjected to the high frequency test. During one revolution of the cams, the armature rotates about three times at a rate of about 10 R. P. M.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. Apparatus for testing an armature which includes a shaft, a core and a commutator assembled with the shaft and coils assembled with the core and connected with bars of the commutator, a rotatable chuck for receiving and driving the armature shaft and providing a ground connection therefor, a driving shaft, gearing connecting the driving shaft with the chuck to impart to the latter rotative speed greater than the speed of the former, contacts engageable with the commutator at spaced points, and means operated by the driving shaft during one revolution thereof for causing the contacts to engage the commutator and for successively establishing connections between test circuits and one or more of the contacts.

2. Apparatus for testing an armature which includes a shaft, a core and a commutator assembled with the shaft and coils assembled with the core and connected with bars of the commutator, a rotatable chuck for receiving and driving the armature shaft and providing a ground connection therefor, a driving shaft, gearing connecting the driving shaft with the chuck to impart to the latter rotative speed greater than the speedof the former, contacts engageable with the commutator at spaced points, a cam support mounted on the driving shaft, a one-revolution clutch for connecting the driving shaft with the cam support, manually operable means for tripping the clutch, cams mounted on the support, and devices respectively operated by the cams during one revolution thereof for causing the contacts to engage the commutator and for successively establishing connections between test circuits and one or more of the contacts.

3. Apparatus for testing an armature which includes a shaft, a core and a commutator assembled with the shaft and coils assembled with the core and connected with bars of the commutator, a rotatable chuck for receiving and driving the armature shaft and providing a ground connection therefor, a driving shaft, gearing connecting the driving shaft with the chuck to impart to the latter rotative speed greater than the speed of the former, contacts engageable with the commutator at spaced points, a cam support mounted on the driving shaft, a one-revolution clutch for connecting the driving shaft with the cam support, manually operable means for tripping the clutch, cams mounted on the support, a carriage supporting two of the contacts and movable to cause them to engage the commutator, means supporting the third contact, a mechanism operated by the carriage for actuating said third contact support to cause it to move said third contact into engagement with the commutator when the carriage moves its contacts into engagement with the commutator and devices respectively operated by the cams for causing movement of the carriage and for successively establishing connections between test circuits and one or more of the contacts.

FLOYD J. FOUST. OLVEN W. CHILDRESS, JR. DWIGHT O. CRIM. ROBERT A. THOMPSON.

References Cited in the file of this patent UNITED STATES PATENTS Number 

